content: /*
   * Copyright 2017 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.reactive4javaflow.impl;
  
  import hu.akarnokd.reactive4javaflow.errors.CompositeThrowable;
  
  import java.lang.invoke.VarHandle;
  import java.util.concurrent.atomic.AtomicReference;
  
  public final class ExceptionHelper {
  
      private ExceptionHelper() {
          throw new IllegalStateException("No instances!");
      }
  
      public static final Throwable TERMINATED = new Terminated();
  
      static final class Terminated extends Error {
  
          Terminated() {
              super("No further exceptions can be emitted through onError. Seeing this error indicates a bug in an operator.");
          }
  
          @Override
          public Throwable fillInStackTrace() {
              return this;
          }
      }
  
      public static boolean addThrowable(AtomicReference<Throwable> errors, Throwable t) {
          for (;;) {
              Throwable a = (Throwable) errors.getAcquire();
              if (a == TERMINATED) {
                  return false;
              }
              Throwable b = CompositeThrowable.combine(a, t);
              if (errors.compareAndSet(a, b)) {
                  return true;
              }
          }
      }
  
      public static boolean addThrowable(Object target, VarHandle ERRORS, Throwable t) {
          for (;;) {
              Throwable a = (Throwable) ERRORS.getAcquire(target);
              if (a == TERMINATED) {
                  return false;
              }
              Throwable b = CompositeThrowable.combine(a, t);
              if (ERRORS.compareAndSet(target, a, b)) {
                  return true;
              }
          }
      }
  
      public static Throwable terminate(Object target, VarHandle ERRORS) {
          Throwable a = (Throwable)ERRORS.getAcquire(target);
          if (a != TERMINATED) {
              a = (Throwable)ERRORS.getAndSet(target, TERMINATED);
          }
          return a;
      }
  
  
      public static Throwable terminate(AtomicReference<Throwable> errors) {
          Throwable a = (Throwable)errors.getAcquire();
          if (a != TERMINATED) {
              a = (Throwable)errors.getAndSet(TERMINATED);
          }
          return a;
      }
  }
  